Tuesday, June 16, 2009

Vatnajökull

Vatnajökull (English: Glacier of Rivers) (IPA: [ˈvahtnaˌjœːkʏtl ̥]) is the largest glacier in Iceland. It is located in the south-east of the island, covering more than 8% of the country. With a size of 8,100 km², it is the largest glacier in Europe in volume (3,100 km³) and the second largest (after Austfonna on Nordaustlandet, Svalbard) in area (not counting the still larger ice cap of Severny Island of Novaya Zemlya, Russia, which is located in the extreme northeast of Europe).The average thickness of the ice is 400 m, with a maximum thickness of 1,000 m. Iceland's highest peak, Hvannadalshnúkur (2,110 m), is located in the southern periphery of Vatnajökull, near Skaftafell National Park. It is classified as an ice cap glacier.Under the glacier, as under many of the glaciers of Iceland, there are several volcanoes. The volcanic lakes, Grímsvötn for example, were the sources of a large glacial lake outburst flood in 1996. The volcano under these lakes also caused a considerable but short-time eruption in the beginning of November 2004. During the last ice age, numerous volcanic eruptions occurred under Vatnajökull, creating many subglacial eruptions. These eruptions formed tuyas, such as Herðubreið which originally sat beneath Vatnajökull during the last ice age.Vatnajökull has been shrinking for some years now, possibly because of climatic changes and recent volcanic activity. Until 1930 it was growing. The phenomenon of Jökulhlaup is at present time confined to Vatnajökull.According to Guinness World Records Vatnajökull is the object of the world's longest sight line, 550 km from Slættaratindur, the highest mountain in the Faroe Islands. GWR state that "owing to the light bending effects of atmospheric refraction, Vatnajökull (2119m), Iceland, can sometimes be seen from the Faroe Islands, 340 miles (550km) away". This may be based on a claimed sighting by a British sailor in 1939. The validity of this record is analysed/undermined in mathematical and atmospheric detail by J.C. Ferranti.[1]